Earlier related questions:

  1. How to solder a 70 °C (158 °F) thermofuse
  2. Using a thermal fuse in a PCB terminal block?

History: I 'normally' soldered a nonresettable thermal fuse, which (of course) failed after soldering.

I have ordered a resettable thermal fuse RY Tf, for 73 degrees (Celcius), after getting a comment from PlasmaHH in question 2 that such components exists.

However, I'm wondering, what happens if I solder these? During soldering, the temperature will go much further than 73 degrees, but will it 'reset' or keep on resetting until the soldering process is finished and it has cooled down enough. Thus will the thermal fuse function normally after soldering?


Yes, they can be soldered. So long as there's no permanent damage to the insulators in the fuse it'll just reset after it cools. The sensing element is a bimetallic strip that has some hysteresis by virtue of being formed slightly convex, it snaps away from the stationary contact as the inside metal expands more than the outside. I've soldered a number of these without issue.

  • \$\begingroup\$ Great, that makes them much easier to solder than nonresettable versions. \$\endgroup\$ – Michel Keijzers Oct 16 '18 at 15:11

The answer to all these linked questions is to read the datasheet! All (well made) components will give details as to how they should be soldered or attached. This will (should) include max temperatures, hold temperatures, times etc. While these may be hard to exactly achieve by hand, it will indicate the regions that are acceptable.


It may seem silly, but: depending on the size of the fuse, the easiest thing to do is to not have heat on the fuse at all. It's easy to use a removable fuse with clips. Solder the clips with high heat for minutes on end and they won't care. Put the fuse in afterward. You'd have to be doing something very strange with your iron to make the clips themselves fail mechanically.

  • \$\begingroup\$ The thermal fuse I have (and it seems they are quite common) has two leads and is not replacable (i.e. not like a normal current fuse which can be attached in its own fuse holder). Or do you mean some manually made 'clip'? \$\endgroup\$ – Michel Keijzers Oct 16 '18 at 15:55
  • 1
    \$\begingroup\$ No, not a manual clip; standard clips by diameter, e.g. 5mm. If you're unable to swap out a through-hold component with a clip insertion component, then this solution won't apply. \$\endgroup\$ – Reinderien Oct 16 '18 at 15:57
  • \$\begingroup\$ If your fuse has leads, another option is add a two-port terminal block and simply screw it in. \$\endgroup\$ – Reinderien Oct 16 '18 at 15:58
  • \$\begingroup\$ Yes, also thought about a terminal block. \$\endgroup\$ – Michel Keijzers Oct 16 '18 at 16:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.